1. Field of the Invention
The present invention relates to the control of a domestic appliance and, in particular, to a remote control system for the control of a cooking appliance.
2. Prior Art
Traditionally, controls for the operation of a cooking appliance such as controls for the heating elements of a cooktop surface as found on an electric range have been located either on the cooktop surface or on a surface which extends vertically from the rear or front of the cooktop surface. Each of these locations have caused problems for either the consumer or the manufacturer.
Selectors, such as buttons or knobs, located on the cooktop surface are susceptible to the collection of dust, food particles and grease thereon and are often subjected to intense heat from the proximately located heating elements. Usually, such cooktop-positioned controls are readily accessible and visible to the operator, but, undesirably, may also be accessible to small children. Furthermore, such controls detract from the space available on the cooktop surface for the heating elements and cause the area around the controls to be difficult to clean.
Many manufacturers of electric ranges place the heating element control selectors on a surface extending vertically from the rear of the cooktop surface. This allows the cooktop surface to be used solely for the heating elements and makes the selectors much less accessible to children. Such selectors are also susceptible to collecting dusts, grease and food particles, but due to their vertical orientation, may be less effected than are cooktop surface positioned controls. However, these rear controls pose additional hazards for the operator as the individual may incur burns or the individual's clothing may be scorched or set on fire when reaching over hot heating elements or over spattering or steaming foods located on the cooktop in order to adjust the controls. Furthermore, rear controls and displays are difficult for some operators to see and the vertical orientation imposes difficulty for some in interpreting the displays or the position of selectors.
Detached control panels for cooktop surfaces have been developed in which the control panel is installed in a countertop proximate the cooktop surface and communicates via wiring to the cooktop surface. Although detached control panels are easy to see and allow the cooktop surface to be used solely for the heating elements, installation of the detached control panel decreases available countertop surface, is limited by the length of cable provided, and increases the manufacturer's costs by the need to provide a means for routing the cable from inside or underneath the cooktop surface to the detached control panel in a recessed manner. Additionally, should the consumer need to replace the cooktop surface, expensive countertop remodeling may be required to accommodate a new detached control panel of a different size and shape or to accommodate a cooktop surface having integral controls.
The concept of providing a remote control unit for a domestic appliance as is provided for many household electronic devices such as television receivers, VCRs and stereo systems, is very attractive. Not only does a remote control provide the operator with freedom of movement while attending to food being cooked on the heating elements, but many of the disadvantages of cooktop-positioned, rear-positioned, and detached controls are eliminated. Specifically, the controls may be positioned such that they are inaccessible to small children and yet are readily accessible and visible to an adult operator. Remote control also does not require the operator to endanger himself/herself by reaching across hot heating elements or food cooking thereon. Also, remote controls do not require space on the cooktop surface, require less cleaning and are easier to clean by being removed from the proximity of the heating elements, and may be located in a non-hostile environment thereby resulting in greater flexibility for the manufacturer in the selection of materials used for control and display and in reducing the cost of the control.
In addition to the above advantages, remote control of heating elements on a cooktop surface requires the provision of several features not necessary for the remote control of digital electronic devices such as television receivers, VCRs, stereo systems and the like. Because the remote control unit for heating elements on a cooktop surface may be introduced into a hostile environment, specifically the heat generated by the heating elements, it is desirable to provide a means for detecting the hostile environment and for taking precautionary steps after such detection. Also, the status of the heating elements should be constantly monitored to ensure proper operation. This, of course, also requires that the communication link between the remote control and the heating elements be monitored to make certain that nothing interferes with the communication path and to ensure that the proper signals are being transmitted and received by both the remote control and the heating elements.
Remote control of microwave ovens and/or convection ovens is disclosed in U.S. Pat. Nos. 4,816,635 and 4,837,414. These remote control units are similar in operation to commercially available VCR control units which are used to read bar codes containing information about the television channel and program start and end times (or program length) for television programs whereby the VCR is programmed for recording. The controls disclosed in U.S. Pat. Nos. 4,816,635 and 4,837,414 are capable of reading bar codes for particular recipes. The bar code designates the cooking times and power levels for a particular recipe. The bar code information is sent via infrared signals to the computer or control within the main oven unit. The main control unit then interprets those infrared signals and controls cooking times and power levels accordingly. No means is provided for communication from the main unit control to the remote control to ensure proper operation of the microwave oven in a continuous manner, nor is the communication link constantly monitored. Thus, the operator is limited to programming via the remote control.
U.S. Pat. No. 4,131,786 discloses a remote control unit which is connected via cables or radio frequency signals to the main control unit for an oven. The remote control unit essentially duplicates the control panel functions of the oven's main control unit. The retention of a fully functional integral control panel together with the implementation of a duplicative remote control unit is one approach to avoiding the need to provide the additional features required for exclusive remote control of an oven; however, this approach, due to redundancy, is expensive to manufacture and defeats many of the advantages obtained by eliminating the need for integral controls, particularly when directed toward control of heating elements on a cooktop surface.
The provision of a remote control unit as the only control unit for heating elements on a cooktop surface is disclosed in European Patent Application No. 90 10 44 85.9 (Publication No. 0 388 727 A2). The remote control unit of this invention, located in the hood above the cooktop surface, communicates via infrared or ultrasonic signals with the heating element controller located on or under the cooktop surface. It is suggested in European Patent Application No. 90 10 44 85.9 that two-way communication be established between the remote control unit and the heating element controller such that when an object obstructs the communication path, the heating element controller sends a signal to the remote control to inform the operator of the presence of the obstruction. However, this invention does not address the problem of an obstruction which has not been removed, faulty signals between the remote control unit and the heating element controller, proper operation of the heating elements, or the introduction of the remote control unit into a hostile environment.
Thus, it is desirable to provide a remote control system for controlling heating elements of a cooking appliance which detects the introduction of the remote control unit into a hostile environment to thereby prevent damage to the remote control unit and to avoid loss of control of the heating elements.
It is also desirable to provide a remote control system for controlling heating elements of a cooking appliance wherein the operation of the heating elements is constantly monitored.
It is also desirable for such a remote control system which ensures that proper communication is established at all times between the remote control unit and the heating element controller.
It is also desirable to provide such a remote control system wherein a permanent obstruction in the communication path, faulty signal transmission or receipt, faulty heating elements, or introduction of the remote control unit into a hostile environment results in the proper shut-down of all active heating elements at an appropriate time following the detection of such problem.